Immunoglobulin M Multiple Myeloma: Case Report of a Rare Variant of Multiple Myeloma with Diagnostic and Treatment Challenges.
Vikram Vikhe, Sarthak Mangal, Krishana Dalvi et al.
✦ AI-curated · Sources linked
Case in brief
A 64-year-old woman presented with three weeks of persistent lower back pain. Testing showed anemia (hemoglobin 9.2 g/dL), an IgM level of 5,070 mg/dL, an M-spike of 3.09 g/dL, and monoclonal IgM lambda with an abnormal free light chain ratio. Bone marrow biopsy showed 25% lambda-restricted plasma cells, and PET-CT demonstrated multiple hypermetabolic lytic lesions in the axial and appendicular skeleton. The findings supported IgM multiple myeloma rather than Waldenström macroglobulinemia. She received bortezomib, lenalidomide, and dexamethasone, with bisphosphonates and thromboprophylaxis; the abstract does not report the outcome.
What made this case unusual
The diagnostic challenge was distinguishing IgM myeloma from Waldenström macroglobulinemia. Plasma-cell infiltration and lytic bone lesions supported myeloma, while lymphoplasmacytic infiltration, hepatosplenomegaly, and hyperviscosity symptoms were absent; MYD88 and CXCR4 mutations were also negative.
Diagnostic / clinical pearl
In an IgM-producing malignancy, integrate marrow morphology, skeletal imaging, protein studies, clinical features, and mutation testing to distinguish plasma-cell myeloma from Waldenström macroglobulinemia.